Press units for moisture removal



Dec. 22, 1964 J. E. POST mass UNITS FOR MOISTURE REMOVAL Filed March 23.196].

TO JOURNAL www FIG?) FIG.4

United States Patent ERESS UNlTS FOR MGR'STURE REMOVAL James E. Post,Samoset Road, Box 367, South Duxhui y, Mass.

Filed Mar. 23, 1961, Ser. No. 97,914 3 Claims. (Cl. 162-358} Thisinvention relates to the extraction of liquid from a moving web or sheetand, more particularly, to press units for use in paper-making machines.for extracting water from a web of pulp or paper that is carried on orbetween a porous material such as a felt member or belt.

A principal object of the present invention is to provide improved pressor pressure units or assemblages for the more efficient and economicalremoval of water from a rapidly moving web or sheet of material such aspaper.

Still another object of the invention is to provide an improved lowerpress unit or assemblage comprising an endless belt or blanket of aresilient material such as rubher having on one surface thereof aplurality or profusion of holes of predetermined depth.

Still another object of the invention is to provide an improved upperpress roll or unit having a porous structure through which hot air orsteam may be passed.

A still further object of the invention is to utilize said improvedupper press roll and lower press unit in combination in, for example, apaper-making machine.

Other objects of the invention will in part be obvious and will in partappear hereinafter.

The invention accordingly comprises the apparatus possessing theconstruction, combination of elements md arrangement of par-ts which areexemplified in the following detailed disclosure and the scope of theapplication of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention,reference should be had to the following detailed description taken inconnection with the accompanying drawings wherein:

FIGURE 1 is an isometric view, with parts in section, showing a web ofwet paper carried by a felt belt passing between the preferred pressunits or assemblages of the invention;

H6. 2 is n isometric view, with parts in section, she ing a web of wetpaper carried between two felt belts passing between the preferred pressunits of the invention; and

FIGS. 3 and 4 are cross-sectional views of the endless belt of the lowerpress unit showing the preferred constructions of the holes or wellspresent in said belt.

in the manufacture of paper, it is generally the practice to convey aweb or sheet of paper, after it is formed on the Fourdrinie-r wire orother sheet-forming device and which contains about 85 percent or moreof water, through the presses and then through the dryers for theremoval of water. In the press part of a paper-making machine, the webof wet paper is carried by the aid of one or more press felts betweenpressure rolls for the purpose of squeezing or pressing water from theweb by pressure exerted between the rolls. These rolls are generallyarranged in vertical or superposed pairs, two, three or more pairs beingemployed. The lower roll, or each lower roll of the press may be asuction roll, that is, provided with means for removing water from thepaper web by the application of a vacuum, or it may be a plain roll,that is, without perforations.

One form of lower press roll which is frequently employed is a metalshell provided with a plurality of perforations which rotate past asuitably positioned suction box. The outer surface of the shell isgenerally provided with a layer or covering of a relatively softmaterial such as rubber which is provided with perforations which are insubstantial alignment with the shell perforations 50 that the wet paperweb conveyed between the press rolls is subject to a vacuum for removingwater therefrom. These suction rolls are generally quite expensive.

The upper or top press roll which may be made of various metals, such ascast iron, brass or bronze jacketed cast iron, or the like, or ofrubber, wood such as maple, stone such as granite or other non-rustingmaterial or composition is always provided with a smooth surface. Thepressure, exerted between the rolls may be due to the weight of theupper press roll alone or to the weight of said roll and additionalpressure applied, for example, to the journals of the upper press roll.

- Heretofore known perforated coated lower press rolls possess severaldisadvantages. For example, since the shell is usually made of metal,difiiculties are frequently encountered in obtaining a strong adherentbond between the metal shell and the covering which is usually rubber.Obviously separation of the covering from the shell can have severalundesirable efiects such as slippage of the covering which may causemisalignment of the perforations and thus appreciably reduce the removalof water by suction, or tearing of the covering so as to necessitateshutdown of the machine. Another difficulty is in securing alignment orregistry of the perforations in the covering with those in theunderlying-metal shell. Still another disadvantage is that when it isdesired to replace or recover a lower press roll, it must be removedfromv the paper-making machine which may be difficult due to the sizeand weight thereof and may also be time consuming thus resulting inexpensive down-time. Another disadvantage resides in the fact that itusually is notpo'ssible to replace the covering on the lower press rollwhile it is still on the machine. It is generally necessary to removethe entire roll and to ship it to the manufacturer thereof thus alsonecessitating considerable and costly shutdowns.

It has been stated, for example, in US. Patent L978,- 982, that many ofthe disadvantages inherent with perforated coated lower press rollsshould be eliminated by employing an endless belt of, for example,rubber, which is provided with perforations therethrough. However, inpaper-making machines traveling over 1200 feet per minute, even thislower press roll construction cannot utilize the full advantage of thesuction due to the element of speed and the time element of the web andfelt in the nip of the press rolls. Moreover, the lower suction pressroll is a highly expensive piece of equipment. In the present invention,there is provided a relatively inexpensive lower press unit which may beused so as to eliminate the above-mentioned disadvantages and which maybe efiectively and efficiently utilized without the need of suction orthe like. This improved lower press unit comprises a plurality of rollsaround which moves an endless belt of, for example, rubber orrubber-like material having .a plurality or profusion of holes or wellsof predetermined depth on the outer surface thereof, that is, on thesurface which comes into contact with the press felt as it is conveyedbetween the upper press roll and lower press unit. The holes may be ofthe same depth or of various depths, however, in no instance do theypenetrate through to the bottom or inner surface of said belt.Provisions are made for guiding and tensioning the endless belt.

Much consideration has also been heretofore given to providing an upperpress roll which had a hard, smooth surface, and which had a lowcoefilcient' of friction and substantially no alfinity for the paperfibers, in other words, it must not pick up paper fibers so as to spoilthe web running under it. This sticking or picking action of paperfibers to the roll is cumulative so that eventually the surface becomesundesirably uneven and bumpy. Sticking of the paper fibers to the upperpress roll may cause the paper to tear which may necessitate greases i9rethreading the paper web through the machine, again with a considerableloss of time, money and production. Metal rolls for the most part can beprovided with a straight or crowned, smooth, hard surface. However,generally such metal rolls possess the disadvantage of readily pickingup paper fibers which, as pointed out, is undesirable. In the presentinvention there is provided a metallic upper press roll of aconstruction such that paper fibers can be prevented from being pickedup thereby or from sticking thereto. The preferred upper press rollcomprises a hollow roll or cylinder of suitably sintered metal having vapredetermined porosity. This roll although having a porous surface whichhas little or no tendency to pick up paper fibers, is also easilyprovided with a smooth, hard, straight 'or crowned surface. Moreover,the present invention also contemplates the introduction of hot air orsteam under suitable pressure into said roll, the hot air or steam thenflowing or permeating through the porous sintered metal roll so as toforce the paper web from the roll, thus minimizing picking problems.Furthermore, the heated upper press roll and the hot air or steamflowing therefrom Will also aid in water removal by vaporizing orevaporating water in the nip formed by the upper press roll and lowerpress unit. 7

Referring now to FIGURE 1 wherein. there is shown a porous press belt10, generally of felt, conveying or carrying a water-'ladened paper webor sheet 12. The press felt 10 and the paper web 12 are advanced orpropelled between the nip of an upper or top press roll or unit 14 and alower or bottom press unit 16 for pressing or squeezing water from paperweb 12. Although only one pair of vertical press units are shown, itshould be understood that two, three or more of such press units may beutilized in a paper-making machine.

The upper press roll 14 preferably comprises an elongated hollow body orstructure having at least its longitudinal wall 13 formed of a suitablethickness of sintered metal. The end walls 20 of the upper press roll 14which need not be formed of sintered metal are provided with journals orshafts 22. The upper press roll 14 is mountedby its journals 22 insuitable supports or bearings (not shown). The choice of the type ofmetal or alloy employed in sintered form depends on the conditions ofservice. Among'the many metals or alloys 4 which may be utilized as theupper press roll in sintered 7 d the hollow center of the sintered metalroll 14 to create a hot surface to iron and help dry the paper web 12.0bviously more water can be extracted from the paper web by employingelevated temperatures. One manner or means by which the hot air orstream from a suitable supply 40 can be injected is, for example,through a condit 42 in each of the roll journals 22. Preferably, the hotair or steam is injected into the upper press roll 14 under a suitablepressure so as to have the hot air or steam flow through the poroussintered metal roll and to vaporize or evaporate water in the nip formedby the upper press roll and lower press unit, thus helping to increasewater removal. The elevated temperatures will also result in vaporizingor evaporating, to some extent, the water pressed into the holes of thebelt, thus achieving more water removal. of steam or hot air pressureutilized will depend on the condition of service. It should also benoted that by forcing the steam or hot air through the porous sinteredmetal roll there should be provided a tendency to force the paper webfrom the roll thus helping to minimize any picking problem. Furthermore,such outward flow of hot air or steam should aid in maintaining the rollclean. The bottom press unit 16 comprises an endless belt, blanket,bolster or the like 24 and a plurality of predeterminedly spaced rollsover which belt 24 moves or travels. In order to support, guide andtension the. endless belt 24 a plurality of rolls are provided, fourrolls 26, 28, and 32 being shown here. These rolls are suitably mountedor supported through their shafts. Rolls 28 and 32, for the most part,hold the endless belt away from nip or press roll 26 but allow the curbless belt to come in contact with roll 26 at a point where it nips withthe upper press roll 14. To insure that inner surface of endless belt 24has sufficient frictional engagement with roll 26 so as to preventslippage therebetween,

at least one of rolls 28, $0 and 32 may function as a tension roll, theothers then functioning as idler or carryform, mention may be made ofbronze, brass, stainless steel, mild steel, cast iron and the like. Thedegree of porosity in the sintered metal may be controlled. The use ofan'upper press roll 14 of any particular degree of porosity will dependupon many factors such as, for example, the grade of paper being run andother operating conditions on the machine. The outer surface of,sintered metal wall 18 can be appropriately machined to provide thedesired smooth, straight or crowned surface. It should be noted that theouter smooth surface of wall 18 contains a profusion of minute pores.however, are too small to mark or to leave any imprint upon the paperweb 12. As pointed out above, the permanently porous surface which isachieved through the use of sintered metal has little or no tendency topick up paper fibers in cases where the paper web comes into directcontact with its surface. This may be due to the trapping of air betweenthe upper press roll and paper web which prevents any picking up orsticking of paper fibers.

The sintered .metal roll may be doctored with steel, Micarta, Monel(trademark of International Nickel Company for nickel-copper corrosionresistant alloys) or other similar type oscillating blades (not shown)in order to prevent wrapping of the upper press roll by the paper Web inthe event of a break.

In one embodiment, means are provided to heat the sintered metal roll.Preferably a hot gas such as, for example, hot air or steam is injectedor introduced into These pores,

ing rolls for the endless belt 24. As shown, upper press roll 14, roll26 and roll 30 are invertical axial alignment while the spaced pair ofrolls 2% and 32 are in horizontal axial alignment and predeterminedlypositioned with respect to the vertically spaced rolls 26 and 30. Atleast one of rolls 26, 28, 30 and 32, for example, roll 26 or 30, isdriven in synchronism with the feed rolls of the press felt 10 so thatthe endless belt travels in the same direction and at the same speed asthe press felt 10. 'It should be pointed out that the endless belt 24,and rolls associated therewith, as well as upper press roll 14, travelat high speeds so as to pass therebetween, paper web and press felt, atrates in excess of 1000 feet per minute. The rolls 26, 28, 30 and 32 maybe constructed of any of the well known suitable materials, such asbrass, stainless steel and the like. The rolls, particularly roll 26, toprovide less wear and thus increased life to endless belt 24, may have asuitable rubber covering therearound. Such rubber covering may also beemployed on mild steel rolls to relieve the corrosion problem present.

The, endless belt 24 preferably comprises a relatively flexible orresilient material such as rubber or rubberlike material or otherpolymericmaterial. The choice of the endless belt material would dependupon the conditions of service such as types of paper to be run, type ofmachine, pressure, temperature, concentration of chemicals that mightbe'involved in the operation and the like. The belt preferably ofrubber, may be manufactured endless on a mandrel, cured in a Vulcanizeror similar vessel and then suitably finished on the mandrel or afterremoval, or made as a belt, cured and then made endless by splicing theends together. The endless belt may be manufactured with or withoutsuitable reinforcement members. Thickness and hardness of the endlessbelt will depend on the type of paper machine, grades of paper,pressures and other operating condi tions. The thickness of the endlessbelt generally is on The amount the order of about one inch although asomewhat thinner or thicker belt may be utilized. The width of the endless belt would be at least equal to or slightly greater than the widthof the paper web 12. Thus, in present commercial paper-making machinesthe width of the endless belt may range from about 50 to 300 inches ormore. It should be mentioned that the upper press roll 14 and otherrolls heretofore mentioned are preferably coextensive in width with theendless belt.

Circumferentially and widthwise, the endless belt 24- is provided on itsouter or upper surface, that is, the surface which comes into contactwith the press felt 10, with a plurality or profusion of holes or wells34 of a depth which is less than the thickness of the belt. The holes 34are preferably predeterminedly spaced to form a definite pattern. Thepattern can be varied depending on the type of paper or paper boardmachine, grades of paper and other operating conditions. A definitepattern of holes is desirable for uniformity of water remaining in thepaper web. The holes 34 will vary in diameter depending upon suchfactors as mentioned above. For example, under many operatingconditions, hole diameters on the order of a sixteenth of an inch may besuitable. However, when pigments or the like are present in the web ofpaper, larger hole diameters, say on the order of an eighth of an inchor bigger, may be employed so as to prevent blocking or clogging of theholes by pigment or other material. It may also be possible to employ anendless belt having therein holes of different diameters. through theendless belt and may thus be termed blind holes may be of the same depthor they may be of various depths such as shown, for example, in FlGS. 3and 4. It should be particularly noted that holes 34 do not penetratecompletely through the endless belt 24. The holes 34 can be drilled intothe surface of the belt or the holes can be moulded into belt orprovided by some other suitable means.

The use of an endless belt of the above construction provides for a moregenerous or wider nip and hence the opportunity of filling up more holeswith water as the belt is passed through the nip at a high speed. Thewater so pressed or entrapped in the holes while passing through the nipis thrown 0r spewed out by centrifugal force from the belt and therebyeliminated from the system. The blind holes in the endless belt also actas tiny reservoirs or wells of water in the area of the nip and the useof heat in the area of the nip will result, to some degree, in thevaporization or evaporation of water from these holes thus resulting inmore or increased water removal. Moreover, the use of the preferredendless belt not only results in conditioning the press felt to carryits maximum capacity in respect to water removal but also permitsincreased felt life due to the softer more cushioned-like nip.

Referring now to FIG. 2 wherein like numbers refer to like elements ofFIG. 1, there is shown in this case a web of paper 12 carried between apair of press felts a and 1%. It is obvious that the use of two feltscan be utilized with the apparatus of FIG. 1 and that the use of asingle felt as shown in FIG. 1 can also be used with the apparatus ofFIG. 2. The press felts 10a and 10b with the paper web 12 therebetweenis advanced between the upper press roll 14 of a construction asheretofore described and a lower press unit 16. In this embodiment, theendless belt 24 travels around two vertically spaced apart rolls 26 and36 which are also in axial alignment with upper press roll 14. Roll 30may be employed for suitably tensioning the endless belt. Roll 26 or 30may be provided with means (not shown) for driving the endless belt inthe same direction and at the same speed as the press felts. Theconstruction of the endless belt and rolls 26 and 39 is as heretoforedescribed.

The holes 34 which extend only partially The apparatus described abovecould be installed at one or more positions on a paper-making machinesuch as, for example, the main press section and hot press positions ona Fourdrinier paper machine, at the main press and primary presses on aCylinder Machine and at the main press or in the pressure roll or drierposition on a Yankee Fourdrinier.

In the preferred operation of the apparatus, as shown in the drawings, apaper 12, after it is formed in the Fourdrinier, is conveyed at a highspeed by one or more press felts 10 between the upper press roll 14 andlower press unit 16. team or hot air under suitable pressure, forexample, 20 to 25 pounds of steam is introduced into the hollow centerof the sintered metal roll 14 to create a hot surface to iron and drythe paper web, particularly in the case where the roll comes into directcontact with the paper web such as shown in FIG. 1. When two felts withthe paper web therebetween are employed such as illustrated in FIG. 2,the heated roll adds to the drying thereof in addition to the normalwater removal by pressure. The steam or hot air is forced out throughthe porous roll and heats not only the paper web and felt in the nip butalso the water which has been pressed or squeezed into the blind holes34 carried by the endless belt 24. The use of such elevated temperaturesaids in increasing water removal by vaporizing or evaporating Water inthe nip including, to some extent, the vaporization or evaporation ofwater held or pressed into the small blind holes carried by the endlessbelt 24. Due to the porosity of the surface of upper press roll 14- ithas little tendency to pick up paper fiber. The elimination of havingpaper fibers picked up and accumulated on the roll is furthered by theoutward flow of hot air or steam from the roll which tends to force thepaper Web away from the roll. Furthermore, the outward flow of hot airor steam from the upper press roll 14 also aids in maintaining the rollclean.

As the rapidly moving endless belt passes through the nip, water pressedand squeezed from the paper web and felt is entrapped or picked up inblind holes 34 and then thrown or spewed out by centrifugal force. Theremoval of water from the paper Web is thus achieved through acombination of pressure, squeezing, heat and centrifugal force.

Although the described improved upper and lower press units arepreferably employed in combination, it should be pointed out that eachpress unit may be utilized in combination with a press roll ofWell-known construction. For example, the improved upper press rollherein described may be employed in conjunction with heretoforewell-known bottom press rolls such as, for example, suction press rollsor other conventional bottom press rolls. It should also be pointed outthat the improved lower press unit having an endless belt provided witha profusion of blind holes on the outer surface thereof may be used incombination with well-known upper press rolls. For example, aconventional upper press roll constructed of a metal such as brass,bronze, stainless steel, mild steel or other metal or alloy,chrome-plated roll, granite, wood and the like could be employed withthe preferred endless belt. The roll may be heated internally or asshown in FIG. 2, externally such as by jet of steam into the nip toelevate the temperature of the surface of the upper press roll and theendless belt. Suitable conduits 44 and jet means 46 can be utilized toprovide a flow of hot gas into the nip. Although the use of suchimproved press units do provide an improved press when used inconjunction with well-known upper or lower press rolls, the preferredand most advantageous combination is when they are used together asshown in the drawings.

The press units of the present invention when used in a paper-makingmachine possess or achieve many significant advantages. For instance,the endless belt is not i suction press rolls.

* of the present invention also eliminates the need for exbonded to thelower press roll and thus, if the belt developed some imperfection orbecame worn from use, it could be removed and replaced without the majordifficulty of removing the entire lower press roll or reconditioning thesurface thereof. In many instances, the endless belt could bereconditioned while in use on the machine. Furthermore, since theendless belt is removable and replaceable it does not take the press outof service for any great length of time nor does it requ le thedifiiculty and expense of removing the entire lower press roll andshipping it to the original manufacturer for repairs or recovery.Moreover, the endless belt eliminates the requirement for the specialand expensive rubber to metal bonding now needed for rolls currentlyemployed. Furthermore, there is eliminated the accurate and expensivedrilling of holes in the rubber coverings utilized in lower Verysignificantly, the endless belt pensive suction boxes or means now usedwith the press rolls. Additionally, the endless belt enables thepapermaking machine to beoperated at higher speeds and provides agreater surface within the nip or area of engagement of the press unitswhere the water can pass from the paper web into the holes of the belt.Moreover, the life of the press felts can be increased considerably dueto the more cushioned-like nip and thus felt costs can be reduced.Additionally, the improved press units improve water removal, permitlower steam costs per ton of paper or, board, improve finish of thepaper web or sheet in cases Where the upper press roll comes in directcontact with the paper web, minimize what is generally known in thepaper industry as picking, provide cleaner felts for longer periods oftime due to the additional springor cushion-like action in the nip whichhas the desirable eifect of keeping the felts open, achieve less cost ofoverall maintenance, less replacement costs, less capital investment andlower cost per ton of paper or board.

Although the improved press rolls have been described in connection witha paper-making machine, it should be pointed out that such press unitsare also applicable to other machines such as of the type used, forexample, in

the manufacture of asbestos or asbestos-cement products.

Since certain changes may be made in the above prod ucts or apparatuswithout departing from the scope of the invention herein involved, it isintended that all matter contained in the above description or shown inthe accompanying drawing shall be interpreted as illustrative and not ina limiting sense.

What is claimed is:

1. A press assembly for use in extracting liquid from a moving web ofmaterial comprising, in combination, an upper press unit and a lowerpress unit, said units defining a nip therebetween, said upper pressunit comprising a hollow roll of sintered metal having a prede terminedporosity and means for heating said roll at least in the area of andadjacent the nip, said lower press unit comprising an endless belt of aresilient ma terial and a plurality of rolls around which said endlessbelt travels, said endless belt having circumferentially and widthwiseon the outer surface thereof a profusion of holes of a depth which isless than the thickness of said endless belt.

2. A press according to claim l wh'erein said endless belt comprisesrubber.

3. A press assembly for use in extracting liquid from a moving web ofmaterial comprising, in combination, an upper press unit and a lowerpress'unit, said units defining anip therebetween, said upper press unitcomprising a hollow roll of sintered metal having a predeterminedporosity and means for supplying a hot gas under pressure into said rollto heat said roll and to provide a flow of hot gas through said roll,said lower press unit comprising'an endless belt of resilient materialand a plurality of rolls around which said endless belt travels, saidendless belt having circumferentially and widthwise on the outer surfacethereof a profusion of predeterminedly spaced holes which extend onlypartially through said endless belt.

References Cited in the tile of this patent UNITED STATES PATENTS1,722,503 Millspaugh July 30, 1929 1,978,982 Barstow Oct. 30, 19341,990,102 Smith Feb. 5, 1935 1,998,046 Ellis Apr. 16, 1935 2,167,544 DeBats et al July 25, 1939 2,209,759 Berry July 30, 1940 2,288,675 BerryJuly 7, 1942 2,997,406 Freeman et al Aug. 22, 1961 3,023,805 Walker Mar.6, 1962 FOREIGN PATENTS 1,198,432 France June 15, 1959 568,264 BelgiumJune 30, 1958 720,165 Great Britain Dec. 15, 1954

1. A PRESS ASSEMBLY FOR USE IN EXTRACTING LIQUID FROM A MOVING WEB OFMATERIAL COMPRISING, IN COMBINATION, AN UPPER PRESS UNIT AND A LOWERPRESS UNIT, SAID UNITS DEFINING A NIP THEREBETWEEN, SAID UPPER PRESSUNIT COMPRISING A HOLLOW ROLL OF SINTERED METAL HAVING A PREDETEMINEDPOROSITY AND MEANS FOR HEATING SAID ROLL AT LEAST IN THE AREA OF ANDADJACENT THE NIP, SAID LOWER PRESS UNIT COMPRISING AN ENDLESS BELT OF ARESILIENT MATERIAL AND A PLURALITY OF ROLLS AROUND WHICH SAID ENDLESSBELT TRAVELS, SAID ENDLESS BELT HAVING CIRCUMFERENTIALLY AND WIDTHWISEON THE OUTER SURFACE THEREOF A PROFUSION